1. Field of the Invention
The present invention relates to an apparatus for processing an integrated query from various sensor networks and a method thereof, and, more particularly, to an apparatus for processing an integrated query from various sensor networks and a method thereof for processing various types of sensor network data obtained from a plurality of heterogeneous sensor nodes and sensor networks.
This work was partly supported by the Information Technology (IT) research and development program of the Korean Ministry of Information and Communication (MIC) and/or the Korean Institute for Information Technology Advancement (IITA) [2006-S-022-01, “Development of USN Middleware Platform Technology”].
2. Description of Related Art
As various types of sensor networks have been installed and used, it has become important to process various types of data collected or obtained from the sensor networks and to provide the processed data to application program. Also, it has been essentially required to integrally process sensor information and data collected from various sensor networks because the types of sensor networks have become diverse.
The sensor network and data collected or obtained from the various sensor networks can be classified into event data, temporal data, and continuous data according to the types thereof.
The event data is data transferred from a sensor network, not sensed by sensor nodes, and denotes a predetermined process or a predetermined operation. That is, the event data is previously defined data. For example, a fire watch sensor network monitors a peripheral environment by requests from an application program and/or a user terminal. If the first watch sensor network transfers a “fire occurrence” signal to an application program and/or a user terminal as the event data. The data transferred from the sensor network to the application program and/or the user terminal means that a predetermined condition is satisfied, not data itself sensed by a sensor node.
The temporal data is data collected and obtained from a sensor network at a predetermined instant time according to a query processing request of an application program and/or a user terminal and returned to the application program and/or the user terminal. The temporal data may be ‘snapshot’. For example, when the fire watch sensor network returns a temperature value that is sensed by each sensor node in real time to the application program and/or the user terminal, the first watch sensor network transfers the temporal data to the application program and/or the user terminal. Unlike the event data, the temporal data is a value sensed by a sensor node. The temporal data can be considered as sensing data captured at a predetermined moment. That is, the temporal data can be considered as stable data.
The continuous data is data sensed by sensor nodes and continuously returned from a sensor network to an application program and/or a user terminal for a predetermined time duration according to a query process request of the application program and/or a user terminal. For example, when the fire watch sensor network senses temperature variation for two hours and returns the sensed temperature variation to the application program and/or the user terminal at the interval of one second according to the request of an application program and/or a user terminal, the fire watch sensor network transfers the continuous data to the application program and/or the user terminal. Unlike the temporal data, the continuous data can be considered as dynamic data because a value sensed by the fire watch sensing network is continuously transferred to an application program and/or a user terminal. The continuous data requires a new processing method differently from the conventional static processing method according to a transferring cycle and the amount of transferred data.
Lately, there have been many studies in progress for developing the method of processing the continuous data. Such a method is similar to a method of processing data stream. Since information to be referred for managing and processing various data types of sensor networks, various properties of data, and methods for processing the data are totally different, a structure of processing data stream is also different.
Although various studies have been in progress for developing technologies for various sensor networks and data types obtained therefrom, there have been not much studies in progress for developing a method for integrally processing various types of sensor data.
Therefore, there is a demand for developing a method for integrally processing various types of sensing information and data, which are collected and obtained from a plurality of heterogeneous sensor networks, using one query.